Scientists have discovered many changes in the back muscles in people with low back pain (LBP). They have reported decreased strength ratios between flexor and extensor muscles. Reaction times, endurance, and coordination are reduced.
The amount and speed of postural sway (trunk movement away from and back to the midline) are increased. Even the number of muscle fibers and the way the muscle fibers work together during muscle contraction are less.
Given these changes, it makes sense that exercise can be used to improve structural, neural, hormonal, and metabolic changes in the muscular systems. With the right kind of exercise, it’s possible to improve strength and structure with the goal of decreasing pain and increasing function. But it’s not clear yet what type and how much exercise works best.
In this study, the effect of isometric exercises of the arms is measured on back and abdominal muscle strength. The researchers asked the question, Are upper-extremity exercises able to load the core stabilizing muscles enough to build strength?
Fourteen healthy adult women were tested in a biomechanics lab in Finland. Surface electromyography (EMG) electrodes were used to test the strength and load of back and abdominal muscles during five test exercises.
A special standing frame was used to measure muscle performance. The series of exercises used for the arms was described in detail with photos included. Positions and exercises that produced the greatest activation of trunk and abdominal muscles were reported.
Shoulder extension using both arms at the same time brought about the greatest EMG changes in the abdominal muscles. Pulling the arm back (like pulling an arrow and the string back on a bow) fired up the deep back muscles on the opposite side. This motion is called horizontal shoulder extension.
The authors concluded that these two exercise motions can be used to build strength and endurance in trunk muscles. Exercise programs of the arms do produce enough load to be included in a rehab program for patients with low back pain. It is necessary to support the pelvis during the activity in order to prevent torque (twist force) on the low back area.